The human auditory path consists of the external ear, the middle ear and the inner ear. In the external ear, sound transmitted from the environment of a human, is collected and transmitted to the tympanic membrane. Sound waves imparting onto the tympanic membrane causes the tympanic membrane to vibrate, whereby sound is transmitted into the middle ear. In the middle ear, the transmitted vibrations are forcing structures of the middle ear, i.e. the stapes, malleus and incus to vibrate, which causes the oval window to vibrate. The vibrations of the oval window are transmitted as energy into the inner ear, where the basilar membrane starts to move causing excitement of nerve cells of the human auditory path.
Hearing impairment may arise in any of the previous mentioned parts of the human auditory path, and in dependency of the place of damage to the auditory path, a hearing loss can be classified as conductive, sensorineural or a mixed hearing loss, which is a combination of a conductive and a sensorineural hearing loss. The most common type of hearing loss is caused by problems with the inner ear or nerve pathways. Although sound transmission through the outer and middle ear to the inner ear may be normal, the information cannot be coded into electrical signals that the brain can use. People with this type of hearing loss may benefit from a hearing aid or a cochlear implant system. A Conductive hearing loss is caused by a blockage of sound transmission through the outer ear and/or middle ear. This can occur due to conditions such as chronic otitis media, otosclerosis (calcification that reduces the mobility of the stapes), malformations of the outer ear or e.g. a perforated eardrum. Conductive hearing loss can be treated in many ways, including using bone anchored hearing systems. The last type of hearing loss is the mixed hearing loss. A mixed hearing loss may arise due to e.g. a chronic infection which affects the auditory pathway, such that the cochlear does not function properly. Such mixed hearing loss may be treated by for example using bone anchored hearing systems.
This disclosure generally relates to bone anchored hearing systems which are designed to use the human body's natural ability to transfer sound through vibration to the inner ear. In a bone conducting system, such as a bone anchored system and/or a non-surgical bone conductive system, the external and middle ear is bypassed, applying a device which transmits vibrations directly into the inner ear. The bone conductive system converts environmental sounds into vibrations, which are transmitted through the skull of a hearing impaired and into the inner ear.
The first bone conductive systems generally consisted of a small titanium implant placed in the bone behind the ear of a hearing impaired. A sound processor that attaches to the implant via the skull of a hearing impaired ensured that sounds could be converted into vibrations, which are transmitted through the implant to the skull bone and into the inner ear. These implanted bone anchoring systems have proven to be very good in transferring vibrations directly into the inner ear, but has the drawback of requiring surgery, which patients that would benefit from a bone anchored hearing solution is often not inclined to undergo in view of improving their hearing.
Accordingly, non-surgical bone conductive hearing solutions have been considered as an alternative. The non-surgical bone conductive hearing solutions generally have the same function as the surgical implants. The most commonly used non-surgical solutions generally comprises a soft band or a head band which attaches the sound processor to the skull of a user allowing vibrational transfer of energy into the auditory path. Additional developments of such systems, has focused on getting rid of the head band and instead apply a more simple patch which is connected to the skin of a skull of a hearing impaired person, and made from a material allowing the patch to transfer a vibrational force to the bone skull. Such patch may comprise an adhesive layer on one side, which adhesive layer is configured to attach a side of the patch to the skin of the skull of the hearing impaired person. On the other opposing side to the adhesive layer, the patch comprises a fixture to which a sound processor device of the bone conductive device is attached. The sound processor is generally build into a device which comprises the signal processing means configured for receiving an acoustic sound signal and transmit said signal via a signal processor to a vibration transferred to the skull of a human person.
The design of bone-anchored/conductive hearing solutions (both surgical and non-surgical system) is continuously optimized in view of improving the vibration transfer to the recipient's skull, but also to create a system which is discreet and cosmetically appealing for the hearing impaired to wear. Especially for non-surgical bone conductive solutions, the distribution of the weight of the signal processor when connected to the patch is important, since the implant part is dispensed with, and the device is merely connected to the surface of the skin of the head of a hearing impaired by a headband holding the device in place and or by e.g an adhesive. Accordingly, it is important that the non-surgical bone conductive solutions can be kept tightly to the skin of a user without falling off due to the weight of the signal processor of the device, while providing a sufficient vibration transfer.
Additional considerations which are to taken into account in the design of non-surgical bone conductive solutions includes minimization of feedback and breathability of the device.
Accordingly, this disclosures aims at providing a non-surgical bone conductive hearing solution that addresses at least some of the above-mentioned considerations for designing an efficient and appealing non-surgical bone conductive device. At least the present disclosure provides an alternative to the non-surgical bone conductive technology, which improves the vibrational transfer, stability and breathability of the device when mounted to the skin of a skull of a hearing impaired user.